Chiral examples 1 | Stereochemistry | Organic chemistry | Khan Academy

[@remixied]

Some people complain about how you repeat the same words when you're writing but I have to say I really appreciate this habit. As someone with severe ADHD trains of thought are like having a handful of really slippery fish and on day where I'm particularly tired or stressed it becomes hard to even focus all the way through someone's sentence. School and homework don't slow down to accommodate these days so I have to work through it. Honestly it helps me a lot when you repeat yourself so I don't forget the topic or the point of what you're getting at. Thank you for all your efforts, you've helped so many!!!

[@coltenben3470]

Sorry to be so offtopic but does anybody know a trick to get back into an Instagram account..? I was dumb lost my login password. I would love any assistance you can offer me

[@sanchi7410]

True for me too (cries in ADHD)

[@LD-ji5sz]

This is perfect! You guys have no idea how much I'd rather have you as my professor. A+ tutors!

[@therealtandoori]

I spent $30 on Sapling, $25 on TOPHAT, $45 on my Course notes... but I barely use any of them, I jot down notes from Khan's videos. God bless.

[@JEFFWHlTE]

the way Khan drew the final molecule, it is definitely not chiral. Since there are no bonds coming in or out, you can simply flip the molecule and it will be superimposable. It would be chiral if there were bonds coming in and out of the page.

[@tunneltrance]

ppl are just leaving negative comments because they are struggling at this subject, there's nothing wrong with how he is teaching

[@SuperPomax]

I don't think the 3D models of the molecule are explicit enough. I can understand why people leave negative comments on this point.

[@ameanoacid6176]

I can understand the negative comments though, I came here because I want to learn more about perspective drawing, I mean this is elementary school chirality. not that it's a bad video, it's just REALLY oversimplified and that's why it doesn't do anything for me honestly because chlorocyclopentane might have a different stereoisomer depending on wether the chlorine atom is "sticking out" or "going into" the drawing in perspective. hence it doenst quite cover the entire theorie of chirality

[@mronion597]

PPL means plane polarised light

[@keyalamwanza8578]

Stanyoko

[@Dragonild]

Sal Khan is really saving my life from 12 years in the past

[@tabnaka]

Think of the "hand" example. Your hands have a front side (ie, palm) and a backside (ie, the back of the hand with knuckles). They have a front and back that remain the same as you rotate. So even though you can make your 2 hands overlap thumbs, index and pink fingers, your palms will be facing in opposite directions. The same thing applies with molecules like in Sals example - they have have front and back sides and can't overlap the Cl and F and still have the same fron/back orientation.

[@pglink]

The way he's drawn the molecules (without dashed and wedged lines) might suggest that they are flat and, therefore, superimposable (like two pieces of bread slapped together to make a sandwich). In reality, they are 3D objects. If the yellow molecule has its Cl atom pointing up and Br down (at the chiral center), then the pink molecule would also have that configuration (as he's drawn it). Slapping the two together would result in one of the Cl atoms pointing up and the other down.

[@SuzannesTutoring]

I read through the comments as well and I still don't get how the very last example was non-superimposable and therefore chiral. You could just flip it and it would indeed be superimposable. ...? (-Big fan. Love your videos!)

[@kingpluto77]

Even though Khan didn't draw the wedges and dashes, they are naturally understood to be there since the two particular carbon atoms are sp3 hybridized atoms meaning their electron geometry would resemble that of a tetrahedral, and in this case, the two C's would also have physical geometry of a tetrahedral. Thus, we can assume that on on the left molecule, the (H) is going back while the (Br) is coming out at you thus making a R config., and in the right image that C has a S config.

[@noahjonathan1]

Also, d and l prefixes refer to optical activity, not chirality. R and S refer to chirality. A molecule can have chiral centers and be optically inactive (meso).

[@pglink]

(Cont.) If you subsequently rotated about the carbon-carbon bond to position both Cl atoms pointing up, then the Br atoms would be in different positions. They are not superimposable, no matter how you try to rotate or twist them. Making a model should convince you.

[@eroybal10]

Hello! I really love your videos and they help so much! Here at 00:23 you named the first molecule you introduced incorrectly. It is not chloro-cyclopentene. It is chloro-cyclopentane. Keep doing what you do! Thank you!

[@jacquelinewhite7738]

Would someone please explain to me how the last molecule is chiral? I know some comments were already made about how you have to assume 3D form, but I can't picture it in my head, nor draw it out, to figure out what is wedged and what is dashed. Help!

[@demetricmccall1782]

One of the carbons is connected to 4 different groups.

[@Sweetysweets1999]

Demetric' McCall you replied 6 years late, pretty sure she figured it out by that time😂😂😂

[@gypsyluv1118]

@@Sweetysweets1999 I’m glad he answered 6 years late bc I just got here and his answer was perfect. Your answer, on the other hand, was useless and inane.

[@zikkirito]

​@@Sweetysweets1999😂😂😂 Prolly hasn't

[@syedasarafatima5241]

Short videos with great lessons I totally love the.way you teach sir.

[@jrhennly]

Sounds like Jeff Goldblum explaining Organic Chem:) Great video, and clear explanation. Thanks!

[@noahjonathan1]

@MrJas1991 It doesn't matter how you turn it because there is only one constituent. It doesn't matter whether the Cl is pointed up or down because it's still in the same location... just pointed differently in space. Try taking a model kit and making 1-chlorocyclopentane and see what happens when you move it around in space.

[@mythic971]

At 4:34 he rotated the molecule 180° on the y-axis but if you rotate it on the z-axis 180° then you will get the mirror image.

[@kingKohli-wk9nv]

That's how mirror images are created

[@JkGEMAR]

@@kingKohli-wk9nv but if we rotate 10 degrees about the z axis, the hydrogen becomes in front, out of the page, am i right?

[@sarahmcdonnell1755]

In 3d though the groups will be pointing out at differently angles

[@majorgeneralmalaise]

A molecule can have more than one chiral center. One of the carbons has 2 hydrogens attached, so it is not chiral (the 4 groups are not different). However, the other carbon in the molecule does have 4 different groups, thus it is chiral. Since the molecule has at least one chiral center, it is chiral.

[@momo237302]

I am taking o. Chem. In college and this really helped thank you so much

[@snafoo131]

You sir, are amazing.

[@noahjonathan1]

The 1 carbon is achiral. You cannot make that molecule chiral if you tried. Again, prove it to yourself by building a model. Then build another model that is a mirror image. Now realize that you can superimpose the two because they are the same.

[@Bl4ckBasecoat]

It Is different, that little angling of the chlorine makes a huge difference. It's like the difference between d-glucose and l-glucose.

[@EScorporations]

Finally! Chirality makes sence!

[@gabiyoga]

thank you!

[@Min-sj8xt]

Thankyou so much for this ☺️

[@SalQ799]

At 4:40 when you say you could have easily drawn it differently...well, my brain is a little confused, but if you had drawn it differently then the mirror-image would have also been different which means you wouldn't be able to superimpose it, right?

[@kathryncline-cook5966]

Bit late, but in this situation, I think drawing the Cl group up or down does not mean anything about its actual location. You'd have to draw out its chair conformation for instance instead of just doing a kekule-type notation. I could be wrong, but I think that's what is happening

[@TOTO6506]

such a great vedio : ) i love it. So clearly

[@SamCableguy]

Bromo......Chloro.....Fluoro....methane! lol Awesome video. Extremely helpful!

[@lilaclilac1907]

Thank you so much! ❤

[@curtpiazza1688]

Great! 😊

[@RaxGamers]

When you say not chiral for the chlorocyclopentane, do you mean it's not achiral? Because chiral is non-superimposable mirror images and that's what they were.

[@maryannepenigma1]

Oh well..He really helped me a lot of my assignment..I understand now!!!!hahahahaha! I thought im gonna be dead by tomorrow because of my homework :P

[@baby00040007]

i like the colors

[@Gurvyonpills]

@Ir0xorz You're saying that the two CH2's would be facing the top CH2------CH2 and the one towards the bottom, right? but that is probably just a different confirmation, like I'm sure you can change the shape to allow the molecule to be achiral. all the substituent are the same after-all.

[@juliana15243]

you're smarter than my textbook.

[@uogf]

This guy explains better than my professor.

[@yoojunnguyen9866]

Exam at 8 am, 2 more hours! Thanks, good review

[@mr.lonely1213]

Listen me

[@dinosaurgoliath]

if you'd flip the molecule over itself it wouldn't be chiral, but we are in three dimensions therefore molecules are not 2 dimensional :)

[@lnr08f]

@lakers1120 No, A molecule can contain chiral carbons and still be achiral. A chiral molecule is a molecule that contains a stereocenter (chiral carbon) and who's mirror image is Not superimposable. If there is a molecule that say, contains two chiral carbons, and has a plane of symmetry, then it's mirror image would be superimposable, so even though the molecule contains chiral carbons it wouldn't be a chiral molecule do to the fact that it's mirror image is superimposable sch freelanceteacher

[@santu1996]

thank you very much

[@Justin2k7]

[M]ethyl - [E]thyl - [P]ropyl - [B]utyl Me Eat Peanut Butter! Best way to memorize these 4 :P

[@AspenWicce]

It would be really awesome if he would script out the lecture instead of winging it. He starts on one thing and seems to jump to a few other things until finally finishing his thought.

[@juliadankanich9171]

Besides rotating, can't you just flip the last example and make it identical to its mirror image?

[@vernalwarrior23]

But that's exactly what the mirror image is

[@xboxsucks12]

+Julia Dankanich He doesn't show it but remember the molecule is 3 dimensional, one atom is in the front and one is in the back, so just pretend the Cl is in the front and the Br is in the back. When you rotate the molecule the Cl moves to the back and the Br moves to the front. Imagine a saw horse

[@ryanronq]

It's in 3D

[@antonyh900]

How many stereo isomers will a compound with 2 chiral centres and an alkene have, will it follow the 2 to power of n rule, or does that just apply to the chiral centres and you simply add 2 on to that for e/z from alkene? So essentially i'm asking would it be 8 or 6?

[@firuzul6963]

why is the last example chiral? wouldnt it be the same if u rotate it 180? can someone help me out?

[@gamefreak2050]

If you rotate the molecule on the left 180 degrees, the Bromine would be on top, rather than the bottom of the chiral carbon :)

[@srianshumahadas7178]

Why can't I rotate it laterally 180 degrees? That'll give me the same molecule!

[@kaustabc7562]

@@srianshumahadas7178 This is a 2D (planar) representation of the molecule. If you want to rotate it out of its plane, you would need its 3D structure. Try to draw the 3D structure of the compound (the carbon atoms will form tetrahedral shapes with the groups surrounding them). You will notice that there is no way of rotating the compound in its 3D structure either which would give its mirror image, and thus the molecule is chiral.

[@andreacorreia2519]

Can someone help me understand why the last molecule is chiral?!

[@watcherthatboxer]

Ah, ok thanks. I was wondering why the last molecule was chiral when it didn't look that way.

[@s0m0c]

Thanks.

[@panmaru101]

do you get paid?? You helped a bunch.

[@vonboy007]

So when you were saying that the C was the chiral atom, does the other C next to it not matter? I thought it was 3 different atoms because the C was in the middle.

[@ibrahim2ibrahim]

wait, in the chlorocyclopentane molecule, why wasn't the carbon in the CH chiral? was it because the rest of pentane is essentially one group? or is it because it's bonded to 2 CH2's. i.e. bonded to non-different groups... please help

[@alexxchavezee]

I was consufused at first but chiral means it's NOT superimposable. That seems dumb.

[@wowyouregoodboo]

señor shaman only seems dumb because you don't know what chiral means

[@SirGarmaples]

Chiral comes from the word for hand in Greek, and as we all know, hands are not superimposable on their mirror images. So it makes sense this way! Anything that isn't superimposable like a hand is, it is NOT chiral.

[@katrinatiga16]

LIFE SAVER

[@yhingtantan938]

What are those Example of chiral organic molecule ? Plsss answer asap coz it's my homework thankyouuu 😫💖

[@Sudharshan1995]

08:05 Its 'conformation' and not 'confirmation' I guess!!! :) :)

[@philster00700]

Ummm, can someone clarify as to why the last example is chiral? If the molecule is strictly in its 2D form as Khan drew it, then it is for sure superimposible (not chiral). Am I missing the fact that it has to be a 3D molecule? Thanks!

[@mosesshikoli8863]

haee

[@LillNugget]

When drawing the mirror images, is the orientation in space different? because on this video and the intro to chiral you drew mirror images where the wedges where the same on both sides but in the stereoisomers and enantiomers video for some of them you changed it like a wedge became a dashed line and vice versa, could you please clarify?

[@btskpop1930]

Thaaaaanks

[@deecandee]

I love O-chem!

[@davembruce]

hi there, could you please tell me if the structures Halothane, desflurane, and isoflurane identify which of the three molecules are chrial please

[@SJ-ig1jc]

Love the channel, but conformation* :D

[@ibrahim2ibrahim]

Dude i heard it, but i wasn't sure what he meant... But I've looked on the internet, and it's because it's essentially one group :P

[@phl3628]

I understand that the last example is chiral, but I'm wondering, specifically, is it a diastereomers?

[@mjohnsimon1337]

Pao Lee I don't think so. I mean, one way to tell for sure is to use R and S configuration, but since there's only 1 chiral center, that kinda just throws that out of the window

[@prem1998rocks]

bro u r great, i scored 120/120 in my iit jee mains exam ty so much

[@medishettykumar680]

+Prem Patil in ur village iit jee exam is over?

[@prem1998rocks]

bitch i was talking about my weekly iit exams!! lol!!

[@medishettykumar680]

kids will be kids :D and their language .. gg

[@pavanbhat3861]

@@medishettykumar680 He probably failed. Ignore him.

[@benygboo]

@Ir0xorz the hydrogen would be coming out of the screen if you rated it 180 degrees

[@yukester004]

How come you can't just rotate your last example 180 degrees to get the same molecule?

[@Pkdababeig]

If you rotate the molecule on the left 180 degrees, the Bromine would be on top, rather than the bottom of the chiral carbon :)

[@SAIGEpaige]

THANK YOU SO MUCH

[@zachariahzehavah7747]

dont ignore the pi bond

[@baby00040007]

Thank you good sir (british accent)

[@3birbsInATrenchcoat]

Sorry but how is the last molecule quiral?

[@biochem86]

he starts explaining that at 1:41

[@sabakhan-qc9di]

01:41

[@yorfredrojasmarchan9516]

Just a remark. I thinhk there's an error in the video since the fisst example seems to be chiral and the person on the video says "achiral". please make clear this doubt. Thanks in advance.

[@mostafafedo89]

Conformation*

[@tanmay_a07]

hindi video plz

[@niloufarassadian589]

you use very simple examples!! :S this is for beginners! please make it a bit harder

[@nihayaturrohmah4230]

#19

[@zkmalik]

everyone says that..

[@Palmar3s]

@lnr08f dude. perfect explanation, just what I needed. thanx

[@oknacom]

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[@the-chipette]

@Justin2k7 hahaha! :)

[@ezelanne]

@mcarrejola81 they are really slow they didn't even get this vid. O.o

[@fredd298]

@MW2Addiction PRove youself

[@iwashungry4hands]

Any Ganem students here? Never say chiral carbon!

[@TheOutlawGames]

please Next time use harder examples. this examples are for beginners 😕

[@LONDHE93]

+Mafia's Note well this is not Khan Academy for 'Mafia's Note', it's for everyone, even beginners. So if this is too easyfor you, either skip forward or go on videos on youtube which cater for your higher level of difficulty

[@TheOutlawGames]

+LONDHE93 He's doing really good videos and helpful thats why i dont wanna go to another channel BTW i passed in the exam (:

[@LONDHE93]

Mafia's Note good job

[@xChemistryFTWx]

Haha probably because they didn't do so well on their organic chemistry test

[@nida2192s]

who even says that? lol

[@hanaizdihar4368]

thank you so much